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HypB is one of the chaperones required for proper nickel insertion into [NiFe]-hydrogenase. Escherichia coli HypB has two potential Ni(II) and Zn(II) binding sites—the N-terminal one and the so-called GTPase one. The metal-loaded HypB–SlyD metallochaperone complex activates nickel release from the N-terminal HypB site. In this work, we focus on the metal selectivity of the two HypB metal binding sites and show that (i) the N-terminal region binds Zn(II) and Ni(II) ions with higher affinity than the G-domain and (ii) the lower affinity G domain binds Zn(II) more effectively than Ni(II). In addition, the high affinity N-terminal domain, both in water and membrane mimicking SDS solution, has a larger affinity towards Zn(II) than Ni(II), while an opposite situation is observed at basic pH; at pH 7.4, the affinity of this region towards both metals is almost the same. The N-terminal HypB region is also more effective in Ni(II) binding than the previously studied SlyD metal binding regions. Considering that the nickel chaperone SlyD activates the release of nickel and blocks the release of zinc from the N-terminal high-affinity metal site of HypB, we may speculate that such pH-dependent metal affinity might modulate HypB interactions with SlyD, being dependent on both pH and the protein's metal status. [ABSTRACT FROM AUTHOR]

Introduction: It is recently becoming clear that there is a significant and underestimated effect of metal coordination on the antimicrobial activity of antimicrobial peptides (AMPs) - potential treasure troves for the design of novel antibiotics. Beyond any doubt, understanding the molecular mechanisms underlying these disorders is a serious challenge for modern science. Aim: The way in which metal ions affect the mode of action of AMPs is far from being understood. They may alter the charge/structure/morphology of a given AMP and therefore enhance the AMP antimicrobial potency. The aim of the project is to understand the relationship between metal coordination, thermodynamic stability, structure, morphology and antimicrobial activity of AMPs. Material and methods: Achieving the overall aim requires a complex experimental approach. Mass spectrometry, potentiometry, ITC and a fruitful combination of nMR, UV-Vis, CD and EPR spectroscopic techniques are used to describe the beautiful bioinorganic chemistry of the studied systems. Antimicrobial assays and studies on regular cell lines establish the biological potency of the novel systems. Results: We have recently elucidated the relationship between Zn(II) coordination, structural, morphological change and antifungal activity of human amylin analogues (pramlintide) and for peptides from the shepherin group (from the plant Capsella bursa pastorsis). We observe a logical sequence of phenomena, each of which is the result of the previous one: (i) Zn(II) coordinates to histidyl imidazoles, (ii) causes a structural change of the peptide, which in turn (iii) results in the formation of fibrils. Conclusions: Ultimately, this chain of structural changes has (iv) biological consequences - the Zn(II)-pramlintide and Zn(II)-shepherin complex fibrils have a strong antifungal effect. A similar effect is not observed neither in the case of free ligands, nor in the case of their complexes with Cu(II). A working hypothesis on the mode of action of such Zn(II) complexes assumes that the formed fibrils can act as needles, physically damaging the fungal cell wall or membrane. [ABSTRACT FROM AUTHOR]

Introduction: Undoubtedly, neurodegenerative Diseases (nD) are one of the most serious diseases in modern society. Understanding the molecular mechanisms underlying these disorders is a challenge for global science. nD are still based on huge number of hypothesis, therefore it is important to find out the mechanism which leads to the pathogenic process. Amyloidogenic proteins are associated with severe neurodegenerative disorders afflicting millions of people worldwide. Aim: The misfolding process leading to protein aggregates is far to be completely understood. However, it is well accepted that many factors are able to influence the morphology and kinetics of amyloids formation. The aim of the project is the understanding of the bioinorganic chemistry of biologically significant copper complexes of the amyloidogenic proteins, in the presence of micelles, which mimic the lipid bilayer, to which the proteins are anchored in vivo. Material and methods: Understanding the coordination properties of the metalpeptide complexes will require a complex experimental approach. Mass spectrometry will be used to study the stoichiometry of metal-complex formation. Potentiometry was allow us to determine the thermodynamic parameters. In order to precisely identify the binding sites, the donor atoms and the coordination geometry of complex species formed in solution at given pH, a fruitful combination of nMR, UV-Vis, CD and EPR spectroscopic techniques have been used. Results: The coordination ability of the amyloidogenic fragment of human Prion Protein (hPrP) is significantly different in the aqueous solution when compared to that containing micelles. Our results prove that the metal binding mode strongly depends on the protein backbone structure. The α-helix structuring of the amyloid hPrP domain influences both the metal coordination sphere and the binding affinity. Conclusions: Essential metal ions are actively involved in several biological events associated with neurodegenerative disorders. The molecular understanding basis of the metal homeostasis and regulations in the cells are critical in identifying the underlying causes for diseases pathophysiology, providing proper diagnosis and treatments. It is also necessary for the development of new therapeutic agents able to treat and prevent their occurrence. [ABSTRACT FROM AUTHOR]

Consecutive histidine repeats are chosen both by nature and by molecular biologists due to their high affinity towards metal ions. Screening of the human genome showed that transcription factors are extremely rich in His tracts. In this work, we examine two of such His-rich regions from forkhead box and MAFA proteins-MB3 (contains 18 His) and MB6 (with 21 His residues), focusing on the affinity and binding modes of Cu and Zn towards the two His-rich regions. In the case of Zn species, the availability of imidazole nitrogen donors enhances metal complex stability. Interestingly, an opposite tendency is observed for Cu complexes at above physiological pH, in which amide nitrogens participate in binding. [ABSTRACT FROM AUTHOR]

Prion proteins (PrP) from different species have the ability to tightly bind Cu2+ ions. Copper coordination sites are located in the disordered and flexible N-terminal region which contains several His anchoring sites. Among them, two His residues are found in the so called amyloidogenic PrP region which is believed to play a key role in the process leading to oligomer and fibril formation. Both chicken and human amyloidogenic regions have a hydrophobic C-terminal region rich in Ala and Val amino acids. Recent findings revealed that this domain undergoes random coil to α-helix structuring upon interaction with membrane models. This interaction might strongly impact metal binding abilities either in terms of donor sets or affinity. In this study we investigated Cu2+ interaction with an amyloidogenic fragment, chPrP105–140, derived from chicken prion protein (chPrP), in different solution environments. The behavior of the peptide and its metal complexes was analyzed in water and in the presence of negative and positive charged membrane mimicking environments formed by sodium dodecyl sulfate (SDS) and dodecyl trimethyl ammonium chloride (DTAC) micelles. The metal coordination sphere, the metal binding affinity and stoichiometry were evaluated by combining spectroscopic and potentiometric methods. Finally we compare copper(ii) interactions with human and chicken amyloidogenic fragments. Our results indicate that the chicken amyloidogenic fragment is a stronger copper ligand than the human amyloidogenic fragment. [ABSTRACT FROM AUTHOR]

The Eighth Central European Conference “Chemistry towards Biology” was held in Brno, Czech Republic, on 28 August–1 September 2016 to bring together experts in biology, chemistry and design of bioactive compounds; promote the exchange of scientific results, methods and ideas; and encourage cooperation between researchers from all over the world. The topics of the conference covered “Chemistry towards Biology”, meaning that the event welcomed chemists working on biology-related problems, biologists using chemical methods, and students and other researchers of the respective areas that fall within the common scope of chemistry and biology. The authors of this manuscript are plenary speakers and other participants of the symposium and members of their research teams. The following summary highlights the major points/topics of the meeting. [ABSTRACT FROM AUTHOR]

Prion diseases, known as Transmissible Spongiform Encephalopathies (TSEs), are a group of fatal neuronal, and to some extent infectious disorders, associated with a pathogenic protein agent called prion protein (PrP). The human prion protein (hPrP) fragment encompassing the 91–127 region, also known as the amyloidogenic domain, comprises two copper-binding sites corresponding to His-96 and His-111 residues that act as anchors for Cu2+ binding. In this work, we investigated Cu2+ interaction with hPrP91–127 in the presence of the anionic surfactant sodium dodecyl sulfate (SDS), which induces a partial α-helix folding of the peptide. Our data indicate that the Cu2+ coordination ability of the amyloidogenic fragment in the presence of SDS micelles is significantly different to that observed in aqueous solution. This is mainly due to the fact that SDS micelles strongly stabilize the formation of the α-helical structure of the peptide backbone, which is well conserved also upon Cu2+ binding, contrary to the random coil conformation mainly assumed by hPrP91–127 in aqueous solutions. Potentiometric and spectroscopic studies clearly indicate that in the case of SDS containing solutions, Cu2+ ions coordinate simultaneously to both imidazoles, while in the case of water solutions, metal ion coordination involves only a single His side chain, which individually acts as an independent Cu2+ anchoring site. [ABSTRACT FROM AUTHOR]

Zn(II) is an inhibitor of SARS-CoV-2′s RNA-dependent RNA polymerase, and chloroquine and hydroxychloroquine are Zn(II) ionophores–this statement gives a curious mind a lot to think about. We show results of the first clinical trials on chloroquine (CQ) and hydroxychloroquine (HCQ) in the treatment of COVID-19, as well as earlier reports on the anticoronaviral properties of these two compounds and of Zn(II) itself. Other FDA-approved Zn(II) ionophores are given a decent amount of attention and are thought of as possible COVID-19 therapeutics. [ABSTRACT FROM AUTHOR]

Alzheimer's disease is a severe disorder that affects millions of people worldwide. It is a very debilitating disease with no cure at the moment. The necessity of finding an effective treatment is very demanding, and the entire scientific community is putting in a lot of effort to address this issue. The major hallmark of Alzheimer's disease is the presence of toxic aggregated species in the brain, impaired metal homeostasis, and high levels of oxidative stress. Rosmarinic acid is a well-known potent antioxidant molecule, the efficacy of which has been proved both in vitro and in vivo. In this study, we investigated the possible role played by rosmarinic acid as a mediator of the copper(II)-induced neurotoxicity. Several spectroscopic techniques and biological assays were applied to characterize the metal complexes and to evaluate the cytotoxicity and the mutagenicity of rosmarinic acid and its Cu(II) complex. Our data indicate that rosmarinic acid is able to interfere with the interaction between amyloid β and Cu(II) by forming an original ternary association. [ABSTRACT FROM AUTHOR]

It is supposed that the presence of poly-His regions in close proximity to poly-Gly domains in snake venoms is related to their biological activity; poly-His/poly-Gly (pHpG) peptides inhibit the activity of metalloproteinases during venom storage via the chelation metal ions, necessary for their proper functioning. This work shows that only the histidyl residues from the N-terminal VDHDHDH motif (but not from the poly-His tag) were the primary Zn(II) binding sites and that the poly-Gly domain situated in the proximity of a central proline residue may play a regulatory role in venom gland protection. The proline induces a kink of the peptide, resulting in steric hindrance, which may modulate the accessibility of potential metal binding sites in the poly-His domain and may, in turn, be one of the regulators of Zn(II) accessibility in the venom gland and therefore a modulator of metalloproteinase activity during venom storage.

A diphenylalanine motif in peptides plays a crucial role in supramolecular systems. The current work represents a novel strategy in which a diphenylalanine motif in the central domain of neuropeptides conserves the specific Zn 2+ binding site and prevents "hopping" of the Zn 2+ ion between alternative metal binding sites. Alternative metal binding sites may also include carboxylic atoms in the terminal domains of a peptide. Therefore, one needs to design a peptide in which the metal will not bind the carboxylic groups in the terminal domains. Herein, we propose that engineering and designing peptides with a diphenylalanine motif in the central domain may yield excellent metal chelators.

Silver is a non-essential element with promising antimicrobial and anticancer properties. This work is a detailed summary of the newest findings on the bioinorganic chemistry of silver, with a special focus on the applications of Ag+ complexes and nanoparticles. The coordination chemistry of silver is given a reasonable amount of attention, summarizing the most common silver binding sites and giving examples of such binding motifs in biologically important proteins. Possible applications of this metal and its complexes in medicine, particularly as antibacterial and antifungal agents and in cancer therapy, are discussed in detail. The most recent data on silver nanoparticles are also summarized., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: The understanding of the bioinorganic and coordination chemistry of metalloproteins containing unusual poly-Xaa sequences, in which a single amino acid is repeated consecutively, is crucial for describing their metal binding-structure-function relationship, and therefore also crucial for understanding their medicinal potential. To the best of our knowledge, this is the first systematic review on metal complexes with polyXaa sequences., Methods: We performed a thorough search of high quality peer reviewed literature on poly-Xaa type of sequences in proteins, focusing on their biological importance and on their interactions with metal ions., Results: 228 papers were included in the review. More than 70% of them discussed the role of metal complexes with the studied types of sequences. In this work, we showed numerous medically important and chemically fascinating examples of possible 'poly-Xaa' metal binding sequences., Conclusion: Poly-Xaa sequences, in which a single amino acid is repeated consecutively, are often not only tempting binding sites for metal ions, but very often, together with the bound metal, serve as structure determinants for entire proteins. This, in turn, can have consequences for the whole organism. Such sequences in bacterial metal chaperones can be a possible target for novel, antimicrobial therapeutics., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Prion proteins (PrP) from different species have the ability to tightly bind Cu 2+ ions. Copper coordination sites are located in the disordered and flexible N-terminal region which contains several His anchoring sites. Among them, two His residues are found in the so called amyloidogenic PrP region which is believed to play a key role in the process leading to oligomer and fibril formation. Both chicken and human amyloidogenic regions have a hydrophobic C-terminal region rich in Ala and Val amino acids. Recent findings revealed that this domain undergoes random coil to α-helix structuring upon interaction with membrane models. This interaction might strongly impact metal binding abilities either in terms of donor sets or affinity. In this study we investigated Cu 2+ interaction with an amyloidogenic fragment, chPrP105-140, derived from chicken prion protein (chPrP), in different solution environments. The behavior of the peptide and its metal complexes was analyzed in water and in the presence of negative and positive charged membrane mimicking environments formed by sodium dodecyl sulfate (SDS) and dodecyl trimethyl ammonium chloride (DTAC) micelles. The metal coordination sphere, the metal binding affinity and stoichiometry were evaluated by combining spectroscopic and potentiometric methods. Finally we compare copper(ii) interactions with human and chicken amyloidogenic fragments. Our results indicate that the chicken amyloidogenic fragment is a stronger copper ligand than the human amyloidogenic fragment.